Aircraft on ground

A group of Airbus aircraft being sealed for long-term grounding at Noi Bai International Airport. Most of them are grounded due to technical issues and are not planned to be withdrawn permanently from the airline's nominal fleet.

Aircraft On Ground or AOG is a universally recognized acronym used within airlines and aircraft operators to indicate that an aircraft is temporarily unairworthy (unable to continue in-service due to technical, maintenance or engineering failures). The term AOG is one of the most serious and costly types of disruptions as it can potentially ground an aircraft for an extended period until maintenance is completed. An AOG can be triggered by a defect as simple as an inoperative light bulb or as complex as a damaged engine or airframe structure which requires replacement. Boeing estimates that a 1-2 hour AOG situation can cost $10,000 to $20,000 and possibly even as high as $150,000 per hour depending on such variables as the type of aircraft and route flown. ^[1] Due to the largely unscheduled nature of AOG's and the likelihood that they often occur in unfavorable locations which lack either inventory, capabilities or facilities, the events can easily lead to significant financial losses.

Causes of AOG incidents

AOG incidents can arise from various factors, including:^{[ citation needed ]}

• Mechanical failures: Unexpected mechanical anomalies or failures during flight or pre-flight checks can ground an aircraft.
• Maintenance delays: Scheduled maintenance that extends beyond the expected timeframe can result in AOG status.
• Unavailable or inaccessible resources, including inventory, tooling, technical knowledge, etc. are all factors that can cause and/or prolong an AOG. Avoidance is the primary objective, with controlling and minimizing downline effects being a secondary objective.
• Supply chain issues: Delays in obtaining necessary parts or components can hinder timely repairs, leading to extended grounding periods ^[2]
• Regulatory compliance: Aircraft may be grounded due to non-compliance with safety regulations or certification requirements.
• AOG can also refer to an aircraft waiting for a flight crew at a different airport, where flight crew are not available. Crew scheduling can designate an inbound deadheading crew, to operate this flight, as "AOG" which makes this crew the highest priority to get seats on the flight. Passengers, even in first class can be "bumped" to accommodate the AOG crew. ^[3]
• AOG maintenance events are designated as such so as to ensure an emphasis on urgency and prioritization.
• While AOG is the most recognizable acronym, the terms OOS (Out Of Service) and AOS (Aircraft Out of Service) can be used somewhat interchangeably to describe events associated with an unairworthy aircraft.

References

1. "Boeing: Boeing Commercial Airplanes Operations Center". Archived from the original on 2008-01-30.
2. Cirium (2020-03-23). "UAE halts all passenger flights for two weeks". Flight Global. Retrieved 2024-11-18.
3. personal experience airline Captain